Three dimentional (3d) robotic micro electro mechanical systems (mems) arm and system

ABSTRACT

A micro assembly having a substrate and an operating plane coupled to the substrate. The operating plane is movable from an in-plane position to an out-of-plane position. One or more electric connections provide electric power from the substrate to the operating plane in the out-of-plane position. A tool is coupled to the operating plane. The tool is operable to receive electric power from the operating plane to perform work.

CLAIM OF PRIORITY

This application is a continuation and claims priority under 35 USC§119(e) to U.S. Patent Application Ser. No. 61/055,038, filed on May 21,2008 and U.S. patent application Ser. No. 12/470,474, filed May 21,2009, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to Micro Electro Mechanical Systems (MEMS), andmore particularly to a three dimensional (3D) MEMS arm and system.

BACKGROUND

Micro ElectroMechanical Systems (MEMS) integrate mechanical elements,sensors, actuators, and/or electronics on a common silicon substratethrough micro fabrication technology. The electronics are oftenfabricated using integrated circuit (IC) process sequences. Themicromechanical components are often fabricated using compatiblemicromachining processes that selectively etch away parts of the siliconwafer or add new structural layers to form the mechanical andelectromechanical devices.

MEMS devices generally range in size from a micrometer (a millionth of ameter) to a millimeter (thousandth of a meter). Common applicationsinclude: inkjet printers that use piezoelectrics or bubble ejection todeposit ink on paper, accelerometers in cars for airbag deployment incollisions, gyroscopes in cars to detect yaw and deploy a roll over baror trigger dynamic stability control, pressure sensors for car tirepressure, disposable blood pressure sensors, displays based on digitallight processing (DLP) technology that has on a chip surface severalhundred thousand micro mirrors and optical switching technology for datacommunications.

SUMMARY

A micro assembly have a substrate and an operating plane coupled to thesubstrate. The operating arm is movable from an in-plane position to anout-of-plane position. One or more electric connections provide electricpower from the substrate to the operating plane in the out-of-planeposition. A tool is coupled to the operating plane. The tool is operableto receive electric power from the operating plane to perform work.

The tool may be, for example, pliers, cutting tool. extension device,hot knife, magnetic bead implanter gun, and biopsy tool. Thus, the microassembly may perform specific functions in three dimensions, such asreaching above and beyond the plane of the chip in order to do work orto obtain and retrieve tangible objects for analysis.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates one embodiment of a MEMS device in accordance withthe present disclosure;

FIGS. 2A-F illustrate force information for the MEMS device;

FIG. 3 illustrates one embodiment of an electrical wire in the MEMSdevice;

FIG. 4 illustrates one embodiment of rotation geometry;

FIG. 5 illustrates further details of the bond pads in accordance withone embodiment;

FIGS. 6A-C illustrate one embodiment of the shark-jaws;

FIGS. 7A-C illustrate one embodiment of a magnetic bead implanter gunand cell breaking points;

FIG. 8 illustrates one embodiment of micropliers;

FIG. 9 illustrates one embodiment of a cutting tool;

FIG. 10 illustrates one embodiment of a biopsy tool;

FIGS. 11A-D illustrate a cauterizing tool; and

FIGS. 12-49 illustrate further details of the MEMS device, includingvarious tools and applications, and fabrication of the device.

DETAILED DESCRIPTION

FIG. 1 illustrates one embodiment of 3D MEMS device that operates atsignificant elevation levels (greater than 1 mm) and performsactivities. The device contains an arm that raises into a positionorthogonal to the chip, allowing one of several different tools to comeinto contact with the space above the chip. Potential tools operated bythe device could include one of any number of different mechanicaldevices: measuring tools, tools suitable for medical applications suchas biopsies, etc.

The device has three major components. First, using on-chip actuation,this design automatically rotates a structure with sizable length (e.g.,mm) to a vertical position that is orthogonal to the plane of the chip.Second, the device is designed to provide electrical power (insulatedhot and ground leads) to the top of the vertical structure once it isupright. Third, at the top of the vertical structure which risessignificantly above the substrate, it provides real estate space formicro-tools that move and perform work. The micro-tool has a telescopicaccordion-like arm with the ability to reach up and grab something over300 μm above the top of the elevated structure which is about 1.5 mmabove the substrate of the chip. In summary, the device is therealization of several features including, for example, automatic 90degrees rotation of released MEMS structures into vertical orientations,electrical power supplied up through the elevated structure, andmicro-tool work and movement at the top of the elevated structure.Applications include nanotechnology, biomedical, micro-manufacturing,micro-fluidics, and micro-sensors. Applications include reaching upabove chip to perform tasks, reaching out off chip to perform tasks andproviding power and/or power leads out of plane. Other applicationsinclude medical applications including: micro-surgery, cut or grab amicro-hunk of tissue, micro-surgical tool, monitoring of bodilyfunctions from inside the body on the micro scale, collecting data orsamples on the micro scale, fertilized egg turner. Micro-toolingapplications include micro-sensing, measuring micro distances, usingMEMS robot to construct other micro-structures, and using MEMS robot torepair objects on the micro scale grabber, extension arm, micro cutterand micro activator.

The device contains an arm that raises into a position orthogonal to thechip, allowing one of several different tools to come into contact withthe space above the chip. Electrical contacts may extend between theout-of-plane platforms and the in-plane platform. The different toolsallow the device to become one of any number of different mechanicaldevices: a measuring tool, a cutter, a grabber, a manipulator, or aspecialized tool designed to complete a specific task.

The geometry of MEMS devices creates a product that is, in effect, a twoand half dimensional object. Therefore, having the ability to raise partof the device and interact in the third dimension will give MEMS devicesnew and progressive 3-D abilities. There are numerous potentialapplications, including interaction with a second chip in a flip-chip orother system or allowing the raised chip to interact on a new levelwithin its working environment. While structure can be raised upmanually (e.g., probe tip actuation), the device, using on-chipactuation, will erect itself into a vertical orientation using its ownmeans. In addition, electrical power will run up the vertical structurein order to run the micro-tools at the end of the operating plane. The3-D micro-robot may perform micro-tasks in the 1 mm to 2 mm rangedistances above the surface of the chip. The 3-D micro-robot may performmicro-tasks in the 1 mm to 2 mm range distances off the edge of thechip. The 3-D micro-robot may perform micro-tasks using electricalenergy in the 3 to 50 volts range with current less than 1.0 milliamp.Designs may fit within the standard 2820μ×6340μ module chip size.

Referring to FIG. 1, the device includes ground lead 1, provides aground for the tools on the top of the operating plane. Hot lead 2includes three hot leads. One hot lead is provided for every thermalactuator required to do a function (i.e. extend the arm, close thegrabber, etc.). These leads connect into the encased oxide (garage)portions of the operating plane. Thermal actuators with jacking system 3uses teeth to incrementally move the jacking system forward. Pin andcross system 4 uses a set of angled cross bars that when drawn forward,apply a force on a set of pins orthogonally attached to the axle of theoperating place. This results in a torque on the axle which causes theoperating plane to rate 90°. There are three cross members on each sideof the rotating axle with 15° between the two cross members. Thermalactuators and latches 5 keep the operating plane secure while it is notbeing elevated. Operating plane 6 is the main body that is beingelevated. The circles are the pores in the operating place. They allowetching trough to the substrate layer which will release the operatingplane 6 from the surface of the chip. In operating plane 6 contains aseries of structures of encased oxide (garages) that will allow P3 to beinsulated and serve as the hot lead for the tool 9. Tool connection 7connects to the tool 9 to provide rigidity, and this is also where thethermal actuator connects for its ground. Thermal actuator for tool 8may be a smaller thermal actuator than the others, so it can fit on thetop of the operating plane. It contains a jacking system to allow thetool to reach its full extension. Tool 9 may be the scissor actionextension arm or other tool option.

In regard to the thermally actuated jack lift system 3, the operatingplane 6 is to be raised 90 degrees by the thermally actuated jackingsystem 3. The jack itself is simply a thermal actuator with a ratchetingcenterpiece designed to incrementally drive a series of cross membercomponents. Each actuation motion travels about 10 μm, and the ratchetteeth are each separated by 4 μm. This means that each actuation pushesthe cross members two teeth, or 8 μm.

The cross member components are designed to translate the force providedby the thermal actuators in order to put a torque on the operating planepivot axle. Pins that are fixed perpendicularly to the axle are guidedby the cross members along a path that is 15 degrees off of the axis.This allows the torque to incrementally raise the operating plane 6 to aposition orthogonal to the MEMS chip. The total distance that the crossmember components need to travel is 18 μm. This means that 2.25actuations are required to reach 90 degrees. There are a total of 6cross member components; a larger number of cross members reduces theforce required for the thermal actuators to achieve plane rotation.Mathematical proofs of FIG. 2 illustrate the key force information forthe MEMS system.

In regard to the operating plane latch system 5, during the releasephase of the SUMMiT V fabrication process, there are turbulent forcesthat can potentially damage a design if the device is not properlysecured to the chip. To minimize the potential for damage, a set ofthermally actuated latches will he utilized to safeguard the device.Located on either side of the operating plane (i.e. the plane to beraised), the latches will secure the plane to the chip face until it istime to raise the plane. At such time, the latches will be released byactivating the thermal actuators, which in turn will free the operatingplane from the face of the chip.

In regard to the operating plane 6, the operating plane providesstability, electrical current, and be the proper size to give height offthe face of the chip. To do this a 1.4795×0.8 mm plane designed that iselectrically charged and fastened at its base to a torsional lift axle.The plane may have the capacity for up to 6 separate circuits, thoughthe main design requires only 2. The interior of the operating plane 6is perforated by release pores, to ensure separation of the 3 structuralpolysilicon layers from the substrate material of the chip. Also on theinterior are the ‘hot’ sides of the electrical tool circuits. To dothis, polysilicon layer 3 is encapsulated in segmented shafts that runthe length of the plane. The shafts are long shells constructed usingpolysilicon layers 1, 2, 3, and 4 (also referred to as P1, polyl, etc.).Layers 1 and 2 serve as the bottom faces of the shell, layer 4 serves asthe top face, and layer 3 serves as the side rails. A single strand ofpolysilicon layer 3 is separated from the shell by the encased oxide andwill run the length of the shaft. In effect, electrical ‘wires’ havebeen created that enable current to be carried to the tool mounted atthe top of the operating plane. See FIG. 3. Along the side edges of theoperating plane 6 run segments that act as grounds for the electricalcircuits.

In regard to leads 1 and 2, the purpose of the leads is to bring powerto the plate when it is raised to 90 degrees. To accomplish this, 3 hotleads and three ground leads are provided that, when the plate is inplace, will connect to the leads which run through the core of theplate. Before the plate can be raised these leads need to be pulled outof the way to clear the path of motion. The geometry for this rotationis illustrated in FIG. 4. Electrostatic forces are used to accomplishthis. By running a lead along the base plate that is next to, but notdirectly beneath, the main leads, a conductor can be used on top of eachbeam to pull it down without letting it touch the conductor. Thisprevents a short circuit that would cause the beam to release back toits original position. During the raising of the plate both the groundand hot leads will be bent out of the way to allow the plate to pass.Once the plate passes, the leads will be released and allowed to contactthe bottom of the elevated plan thus completing the circuit. This iswill provide power to the top of the plate. To ensure this componentwill work properly it is necessary to calculate the force developed bythe charge field below the beam, so that the proper voltage is passedthrough the conducting plate. These calculations allow the actual tipdisplacement of the beam to be estimated using beam theory. From thecalculation for one beam, the force needed to lower the beam a distanceof 2 μm is 2.241 μN. To generate this force it is necessary to have acharge difference of approximately 35 volts between the plates. Thisvoltage must be somewhat higher in practice due to the number of arms tobe lowered and because it is not an ideal situation. After examining thegeometry of the plate bottom and its rotation, the minimum amount theleads can be lowered to allow for clearance is 1.89 μm. In order toallow for the plate to shift it is advisable to lower it as far aspossible, which will be 2 μm.

One major area of concern in the original design of the liftingmechanism for the plate was running power up to the top. In fact thiswas one of our main design objectives. One of the challenges facing thedesign team was to be able to raise the plate and then connect the powerin such a way that the power lines did not interfere with the plate onits way up. To accomplish this the leads were designed as cantileverbeams that could be stressed out of the way and allowed to snap back into position after the plate was raised to its full height. For thisapplication the team chose to use an electrostatic pull down effect onthe beams to bend them low enough to gain the clearance required. Usingthe formulas for beam bending and electromagnetic attraction forcebetween parallel plates, the team was able to derive a method to notonly determine the voltage required to “snap down” our current design,but how a redesign could be done to reduce the voltage required and toprevent arcing between the charged plate and the beam being pulled.

Part of the design takes into account the possibility of a shortcircuit; this involved placing the actual beam having the electrostaticforce applied in the layer above the beam that needed to be cleared ofthe plate. Thus, the team assured that the beam would not touch anylayers. This change in design had major effects on the math model forthe electrostatic snap down, because the force that was being appliedover an area was being transferred to a non-central non-end point on adifferent beam. This required the use of the parallel plate forceequation and the non-central point beam deflection equation, each usingthe size and shape of the respective beam. Basic assumption could bemade: the beam would act linearly in bending, the cross section wouldremain uniform, and the electromagnetic field produced by the basecharging plate would be uniform. For simplicity sake the force on thebeam due to gravitational acceleration was ignored as well. With theseassumptions in place the entire equation became a simple algebraicexpression with either data values that the design team could set orchange as needed, or material constants. From this simple equation theteam was able to derive an expression for the voltage required to movethe beam a certain maximum distance. Once the maximum distance that thebeam can moved has been obtained, work can go into determining theactual distance it would have to travel to clear the rotation of theoperating plane. Then those beams could snap back in to place and linkup for the required

In regards to the scissor action extension gripper or other tool 9, thescissor action extension gripper is located at the end of the operatingplane and provides the ability to extend a tool beyond the planesurface. Two gripping jaws, named shark jaws, are attached to the end ofthe extension system, allowing the device to grasp three-dimensionalobjects as the system extends. There are a multitude of micro tools 9that can be affixed to the gripper system (wrenches, sensors, cutters,etc.).

The scissor action extension gripper is powered by a single thermalactuator, which is connected to a bearing on the jack system 3. As thethermal actuator is charged and displacement occurs, the bearing ispulled by the thermal actuator. The bearing is connected to a stationarybearing on the jacking system 3 through a series of bearings and beams.The stationary bearing has two functions as the pivot point for thejacking system 3 and as the connection for the struts that hold the jacksystem 3 in place. To the right of the stationary bearing lies thedevice that performs the action of extension. It is essentially 3 rowsof 5 bearings per row, each connected by a simple beam. As the thermalactuator pulls on the bearing, the angles of the beams decrease, thuscausing the beams to extend in the opposite direction of the thermalactuator's pull. The decreasing angle of the beams thus causes the sharkjaws to clasp towards each other.

The shark jaws have serrated edges in order to minimize the surfacecontact between the jaws and the object to be grasped. As the contactarea between the two surfaces is decreased, the magnitude of Van derWaal's and stictional forces is decreased, facilitating the release ofthe object.

Regarding the bond pads, FIG. 5 provides details of the bond pads andtheir applications.

The device, in the SUMMiTV application, relies on being able to use theinteraction of the cross-members in P1, P2, and P4 with the bar in P3 tocreate rotational movement. Additionally the gripper system uses P1, P2,and P4 to make two separate bars with hinge pins that are comprised ofP1, P2, P3 and P4, allowing the bars to rotate and the scissor-jack toexpand and contract.

The Sandia Ultra-planar, Multi-level MEMS Technology 5 (SUMMiT V™)Fabrication Process is a five-layer polycrystalline silicon surfacemicromachining process (one ground plane/electrical interconnect layerand four mechanical layers). It is a batch fabrication process usingconventional IC processing tools. Using this technology, high volume,low-cost production can be achieved. The processing challenges,including topography and film stress, are overcome using methods similarto those used in the SUMMiT V™ Process: topography issues are mitigatedby using Chemical-Mechanical Polishing (CMP) to achieve planarization,and stress is maintain at low levels using a propriety process.

MEMS are also produced in the SUMMiT V™ Fabrication Process byalternately depositing a film, photolithographically patterning thefilm, and then performing chemical etching. By repeating this processwith layers of silicon dioxide and polycrystalline silicon, extremelycomplex, inter-connected three-dimensional shapes can be formed. Thephotolithographic patterning is achieved with a series oftwo-dimensional “masks” that define the patterns to be etched. TheSUMMiT V™ process uses 14 individual masks in the process.

The functionality of the micro-robotic arm lies in its ability toaccommodate a wide assortment of tools for a variety of purposes. Thetools 9 are detailed below.

FIG. 6A illustrates the scissor action extension gripper 20. It islocated at the end of the operating plane and provides the ability toextend a tool beyond the plane surface. Two gripping jaws, named sharkjaws, are attached to the end of the extension system, allowing thedevice to grasp three-dimensional objects as the system extends. Thereare a multitude of micro tools that can be affixed to the gripper system(wrenches, sensors, cutters, etc.).

The scissor action extension gripper is powered by a single thermalactuator, which is connected to a bearing on the jack system. As thethermal actuator is charged and displacement occurs, the bearing ispulled by the thermal actuator. The bearing is connected to a stationarybearing on the jacking system through a series of bearings and beams.The stationary bearing has two functions as the pivot point for thejacking system and as the connection for the struts that hold the jacksystem in place. To the right of the stationary bearing lies the devicethat performs the action of extension. It is essentially 3 rows of 5bearings per row, each connected by a simple beam. As the thermalactuator pulls on the bearing, the angles of the beams decrease, thuscausing the beams to extend in the opposite direction of the thermalactuator's pull. The decreasing angle of the beams thus causes the sharkjaws to clasp towards each other.

The shark jaws have serrated edges in order to minimize the surfacecontact between the jaws and the object to be grasped. As the contactarea between the two surfaces is decreased, the magnitude of Van derWaal's and stictional forces is decreased, facilitating the release ofthe object.

The extension distance of the gripper is a function of the thermalactuator's displacement. A maximum thermal actuator displacement of 15 mresults in a reach distance of 319.41 m. There is a linear relationshipbetween the displacement of the thermal actuator and how far the gripperreaches into space (see FIG. 6B). The relationship can be expressed as:

Extension=(δ_(TA))*21.214

-   -   Where: δ_(TA)—Displacement of the thermal actuator

The force exerted by the teeth of the shark jaws is dependent on twoparameters: the displacement of the thermal actuator, and the locationof the contact point between the jaws and the object to be grasped. Anobject near the end of the shark jaws' grasp will not receive as muchforce as an object near the joint, or pivot point, of the jaws. Thisforce is dependent on the moment at the pivot point for the jaws.

$M = {\left( \frac{F_{TA}}{2} \right)\delta_{v}}$

Where: δ_(v)—Vertical displacement of the bearings attached to thethermal actuator

-   -   F_(TA)—Force exerted by the thermal actuator, which is 612.5 μN

The linear relationship between the displacement of the thermal actuator(δ_(TA)), and δ_(v) can be expressed as: δ_(v)=−0.1963δ_(TA)+59.611 (seeFIG. 3). Using this relationship, the force exerted at the contact pointon the jaws can be expressed as:

${F\left( {x_{0},\delta_{TA}} \right)} = {\frac{M}{x_{0}} = {\frac{F_{TA}\delta_{v}}{2\; x_{0}} = \frac{F_{TA}\left( {{\left( {- 0.1963} \right)\left( \delta_{TA} \right)} + 59.611} \right)}{2\; x_{0}}}}$

-   -   Where: x₀—Distance from the joint of the jaws to the contact        point

FIGS. 7A and 7B illustrates a magnetic bead implanter gun 30. Theproblem with current magnetic bead technologies is the failure tospecifically target an individual cell for sorting purposed. In order toaffix magnetic beads to a certain type of cell, the beads are put intosolution with the cells and then randomly attract to one another. Thiscan be problematic If the researcher only wants to collect a unique cellout of a group. The magnetic bead implanter gun (MBIG) solves thisproblem by shooting a single bead into an individual cell, breaking themembrane and becoming Immersed m the cell's cytoplasmic fluid.

The magnetic bead is fit into the two circular holes at the end of theMBIG. The holes serve the purpose of holding the magnetic bead in placebecause the magnetic bead's diameter is much greater than the holes'diameter.

Cold finger technology is used in the MBIG to secure the magnetic beadwhile the operating plane rotates into an orthogonal position. The P2and P4 layers actually hold onto the magnetic bead while the P3 layerprovides the thermal expansion necessary for the MBIG's deformation. TheP3 layer is attached to the P4 layer via a small square of Sac-Ox nearthe end of the gun, and as a current is applied to the P3 layer itexpands and consequentially raises the P4 layer a distance of severalmicrons. Once expanded, a magnetic bead can be placed between thelayers.

The bead is shot from the MBIG via a ramming rod that is connected to athermal actuator. When the thermal actuator is activated and physicallydisplaced, this drives the ramming rod into the bead. The ramming rod isin P3, so it is necessary for the P3 layer attached to the body of thegun to thermally expand and rise out of the way so the layers will notcollide upon impact.

The MBIG is designed so that a bead can successfully puncture a cell'sexterior membrane. FIG. 7C shows several varieties of single celledorganisms and their corresponding pressures needed to break the cellmembrane. The salmonella cell has the largest measured breaking pressurewith 10.13 MPa, so the MBIG should deliver a bead at a relatively higherpressure. The pressure exerted on the bead can be calculated by dividingthe thermal actuator's exerted force by the area of the ramming rod thatimpacts the bead, or:

$P = {\frac{F}{A} = {\frac{612.5\mspace{14mu} \mu \; N}{14\mspace{14mu} \mu \; {mx}\; 2.25\mspace{14mu} \mu \; M} = {19.44\mspace{14mu} {MPa}}}}$

Thus, the MBIG delivers an appropriate pressure to break the membrane ofa cell. It should also be noted that the cell will not be permanentlydamaged by this process. Due to the elastic properties of cells, theywill actually expand in order to accommodate the newly acquired magneticbead. Once the magnetic bead is inside the cell, it will be manipulatedwith an electromagnetic field in order to maneuver the cell-bead pair toa desired location.

FIG. 8 illustrates micropliers 40. Due to an enlarged contact surfacearea, the micropliers are an ideal tool for holding onto large objects.The pliers are driven by a thermal actuator that pulls on a bearing thatis connected to a stationary bearing through a series of beams. Thestationary bearing serves as the pivot point for the pliers and as theconnection for the struts.

FIG. 9 illustrates cutting tool 50. The cutting tool was designed to cutan object with its sharp edges. Driven by the same mechanism as themicropliers, the two heads of the tool pull together and pinch a verysmall contact area. The elongated beams of the cutting tool allow for agreater moment to occur at the pivot point, resulting in a higher forceexerted at the contact point.

FIG. 10 illustrates biopsy tool 60. The tool was based on the shark jawstool and thus is very similar in shape and operation. Calculations forextension are the same as those for the shark-jaws tool because it usesan identical scissor jack, thus the maximum thermal actuatordisplacement of 15 μm results in a reach distance of 319 μm. Althoughthe scissor jack system is the same, the end of the tool operatesdifferently. The basic shape is similar to the shark jaws in order tobest fit the compacted scissor jack shape. However instead of a curvedmeeting of teeth, the biopsy tool 60 features straight edges that cometogether at one time, instead of rotating through each other. The platesthat make up the head of the tool are replaced by a similarly shapedretaining device. This tool head is made by constructing a half-garagefor each side of the head, using P2, P3, P4, and the Sac-Ox layers forthe walls on three sides, but leaving out the P3 layer on the interiorside so that material can enter into the space between the P2 and P4layers as the two half-garages come together. This material can then beretrieved and examined.

FIGS. 11A-11D illustrate the cauterizing tool 70. There are many aspectsof medicine that can benefit from micro scale tools and procedures, forthe simple reason that the area of interest is almost always crowded byother sensitive organs and tissue. In order to cause the least amount ofdamage while affecting repairs it would seem prudent to have the leastinvasive tool that is capable of doing the job. Preventative care is aparticular case that a tool should be able to address. The heart is thecenter of everything that keeps the human body functioning, and excessprotein in the body can and will build up not only In veins and arteriesbut also on the valves of the heart. Like any well running machine theseforeign inclusions will cause wear and tear. These build ups on theheart valves lead to the most frequent cause of strokes to date, the faton the valves can break off and get pumped through that heart at a highrate of speed then jam itself up in a capillary. The back up pressurecaused by this blockage can lead to a stroke. Current procedures toremove the blockages are messy, invasive, and not very reliable. Openheart surgeries, and valve replacement, are the best solutions to removethese fatty deposits. Any procedure that involves cutting the heart openand replacing a piece of it with something artificial is going to betraumatizing, and there is also a fear of the body rejecting the newpart. To avoid this type of complication new methods must be developedto battle the unwanted deposits in both the arteries and veins of thebody.

The MEMS micro torch is one such device that addresses theaforementioned problems. For most current high precision cuttingoperations doctors have used lasers. The applications of lasers in thefield of medicine have aided the doctors to no end in performing precisesurgical cuts and operations, but they still do not address how onereaches inside the heart without resulting in damage. With a MEMS devicethis could change drastically. Because of its small size and powerrequirements, a MEMS device would be ideal for mounting onto the frontan arthroscope to give surgeons a means of interacting with andmanipulating an object in teal time. Aside from the obvious advantage ofcausing less damage to the patient, this tool would allow for surgery tobe performed in areas that are dangerous to reach. For this to be usefula precision device that could reach out above itself and do work isnecessary. The same device should also be able to retract andreapproach, giving it the ability to make multiple passes and do manytasks. Because the device is small and batch fabricated, sterilizationwould not be necessary, simply replacing the tip of the arthroscope witha clean one is sufficient.

A tool that makes precise, measured cuts is needed for theaforementioned MEMS application. Cuts are normally made with surgicalknives, but more recently the cuts are being made by either lasers orheated cutters. Heating something on this scale has proven to be bothsimple and reliable as evidenced by the thermal actuators. The abilityto heat a rod or beam coupled with the ability to reach above the planeresults in the building blocks for a micro scale precision cuttingtorch, but the design needs a way to retract.

To retract the jacking mechanism once it is elevated a few things mustbe done. First the teeth that enable the jacking system to work must bereleased. To accomplish this, an interlinked system involving a thermalactuator and mechanical linkages have been designed. This apparatus didrequire that the interim of the jacking system in both the actuator andthe stationary ratcheting device be redesigned to allow for release ofthe teeth. Once the redesign was complete the teeth could be pulled backwith a single power source, in essence giving the thermally actuatedjacking system a reset button. Enabling the system to retract was thefirst hurdle of the design. To add reliability to the retraction andmake it uniform, a spring is attached to the rear of the rod that isbeing extended, which will apply a spring force and retract the rod morerapidly than simply releasing the ratcheting mechanism. This was addedbecause the device is expected to act not only in a fluid medium, but inany direction necessary, and gravity could not be relied upon to retractthe rod.

For the issue of bring heat to the target area, the decision was made toutilize the same system as the beams in the thermal actuators. Since thedesire is for simple heat and not a forced translation, only two sidebeams are truly needed. But a problem arose in the area of poweringthese beams. They would be moving out and back many times in even themost rudimentary surgery, and the beams themselves would be stressedconstantly. To avoid excess stress on the jacking system and the beamspossibly snapping under the cycling stress, the design was modified sothat the beams were curved. The curved shapes acts much the same aspre-stressing on a spring, it affords the rod more length to extendwithout having to actually stretch the beams that are built across it.This will also reduce the required amount of force to extend the baserod in comparison to if the side beams were originally straight.

FIGS. 12-49 illustrate further information for the MEMS device.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A micro assembly, comprising: a substrate; an operating plane coupledto the substrate and movable from an in-plane position to anout-of-plane position; one or more electric connections providingelectric power from the substrate to the operating plane in theout-of-plane position; a tool coupled to the operating plane; and thetool operable to receive electric power from the operating plane toperform work.
 2. The micro assembly of claim 1, the electric connectioncomprising electric leads between the substrate to the operating plane.3. The micro assembly of claim 2, the electric connection furthercomprising conductive elements in the operating plane extending from theelectric leads to one or more power points for the tool, wherein thepower points may be at the top of the operating plane or otherwiselocated on the operating plane.
 4. The micro assembly of claim 1,wherein the substrate comprises a chip.
 5. The micro assembly of claim1, wherein the operating plane comprises an arm.
 6. The micro assemblyof claim 1, further comprising a tool connection connecting the tool tothe operating plane.
 7. The micro assembly of claim 1, the toolconnection providing rigidity to the tool.
 8. The micro assembly ofclaim 1, wherein the tool is integral with the operating plane.
 9. Themicro assembly of claim 1, wherein the tool is detachable from theoperating plane.
 10. The micro assembly of claim 1, wherein the toolcomprises one of pliers, cutting tool. extension device, hot knife,magnetic bead implanter gun, and biopsy tool.
 11. The micro assembly ofclaim 1, further comprising a jacking system operable to move theoperating plane from the in-plane position to the out-of-plane position.12. The micro assembly of claim 1, further comprising a thermal actuatorto convert electric power into mechanical motion for the tool.
 13. Amethod for performing work in a micro environment, comprising: moving anoperating plane coupled to a substrate from an in-plane position to anout-of-plane position; providing electric power from the substrate tothe operating plane; using the electric power to operate a tool coupledto the operating plane when the operating plane is in the out-of-planeposition.
 14. A micro assembly, comprising: a substrate; an operatingplane coupled to the substrate and movable from an in-plane position toan out-of-plane position; means for providing electric power from thesubstrate to the operating plane in the out-of-plane position; and meansfor operating a tool coupled to the operating plane using the electricpower.